Gastight and gas-filled package and method of making it



May 2, 1950 s. BERGsTElN 2,506,056

GAS-TIGHT AND GAS-FILLED PACKAGE AND METHOD OF MAKING IT 2 Sheets-Sheet1 Filed Oct. 6, 1945 1N VEN TOR. 5mm/1. fzmsrE/N.

ATTORNEYS.

Fragt 10.

May 2, 1950 s. BERGSTEIN 2,506,056

GAS-TIGHT AND GAS-FILLED PACKAGE AND METHOD oF MAKING 1T Filed Oct. 6.1945 2 Sheets-Sheet 2 IN I 'EN TOR. 541141151. 5f/565 'rf/N.

ATTORNEYS.

Patented May 2, 1950 zsoaoss i UNITED STATES -PATENT oFFicE GAS-TIGHTAND GAS-FILLED PACKAGE AND METHOD F MAKING IT samuel Burgum, cincinnati,ohm Application october s, 194s, serai Nn. 620,124

(ci. zza-,3.5)

8 Claims. l

My invention relates to packages made of or comprising paperboard whichhave the attribute of gas-tightness, so as to protect the contents fromexternal gases, or to permit the maintenance of the contents in anatmosphere of protective gas which is prevented from diffusing to theouter air. The packages are preferably of the general type of knock-downor folding paperboard cartons or containers and capable of use as such.

Hitherto the only significantly gas-tight results which have beenachieved in packages of this kind, were achieved by subjecting the lledand closed package to an all-over clip in a bath of coating substancecapable of forming a gas-tight lm continuously over all externalsurfaces of the package. For modes of making and gassing such packages,reference is made to my copending application, Serial No. 557,984, iiledOctober 10, 1944, now Patent No. 2,442,161 and entitled Method of makinggas lled flexible containers, and to my copending application, SerialNo. 553,374, iiled September 9, 1944, and entitled Method of gassingfilled packages.

Good results may be obtained in this way; but the practice of anover-all dip entails certain disadvantages which it is an object of thisinvention to overcome. For one thing, since paperboard itself readilypermits the diiusion of gas, the gas-tight result is wholly dependentupon the continuity and integrity of a lm of coating substance whichmust be applied thickly in order to assure continuity and integrity, andwhich is an external nlm of large area, hence peculiarly susceptible tomechanical disruption. 'I'he hnforming coating is a hot-melt substance,the use of which subjects the whole submerged package to a substantialdegree of heat. This sometimes has undesirable effects on the contentsof the package. Moreover, the heating of the package during dippingproduces expansion of contained air or other gas, the consequentexpulsion of which tends to blow holes in the coating, thus complicatingthe problem of producing a continuous and imperforate film. An over-allexternal, heavy film is also detrimental to the appearance of thepackage.

It is an object of this invention to provide means and methods wherebyequivalent gastightness can be achieved without the need of an all-overdip, which not only avoids these dimculties, but provides economies inoperation, as well as in the quantity of coating substance required.

These and other objects which will become apparent as the descriptionproceeds, I accomplish in those structures and procedures of which Ishall now describe exemplary embodiments. Reference is made to thedrawings, wherein:

Figure 1 is a, diagrammatic showing of a mode of coating and laminating.

Figure 2 is a diagrammatic cross section of a composite board.

Figure 3 is a plan view of a carton blank.

Figure 4 is a partial cross-sectional view of an edge-treated boardportion, taken along the line 4-4 of Figure 3.

Figure 5 is a partial plan view of a tubed carton edge-treated as inFigure 4.

Figure 6 is a cross-sectional view of the longitudinal seam in atubularcarton edge-treated as in Figures 4 and 5, and taken along theline 6--6 of the latter figure.

Figure 'l is a partial plan view of a tubed carton the longitudinal seamof which has been treated in another fashion.

Figure 8 is a cross-sectional view of the longitudinal seam in a tubularcarton in which the seam has been treated after formation, and is takenalong the line 8-8 of Figure 7.

Figure 9 is a perspective view of a, carton after filling and in theprocess of being closed.

Figure l0 is a perspective view of a completed, gassed package.

Figure 11 is a perspective View of a carton showing the result of atreatment of the longitudinal seam after the carton is erected..

Figure 12 is a plan View of a, tubed carton i1- lustrating yet anothermode of treating the 1ongitudinal seam.

Figure 13 is a perspective view of a carton showing a similar treatmentapplied after the carton has been squared up.

Figure 14 is an elevational View with lparts in section of a board-edgetreating mechanism.

Figure 15 is a cross-section thereof taken along the line I5-I5 ofFigure 14.

Figure 16 is a perspective View, with a part in.

section, showing the result of an edge treatment. Figure 1'7 is adiagrammatic representation of 3 apparatus which may be used inlongitudinal seam formation.

Figure 18 is a section taken along the line lag- I8 of Figure 17.

Figure 19 'is a cross-sectional view of'a completed seam formed as inFigure 17.

It is possible, by plying a gas-proof web to a layer of paperboard, tomake a composite which is resistant to the passage of gas. But this byno means solves the problem of providing a gasproof package. Paperboardis itself pervious to the passage of gas throughout its body in alldirections. Hence, in all seams and closures gas can escape, ordiffusion of gas can take place, through the free edges of thepaperboard. Hitherto there was no solution for this problem exceptingthe all-over dip mentioned above, which not only entails the diicultiesset forth, but renders the use of a gas-tight body ply substantiallynugatory.

The present invention is based on the concepts that if a web ofpaperboard or other material from which a knock-down carton is formedcan be made or treated so as to be gas-tight in the direction of itsthickness (i. e. so that as a membrane it will not permit the passage ordiffusion of gas) and if a carton can be formed of it and can be treatedas to the longitudinal seam in such manner that the assembly of bodywalls will form a gas-tight, tubular structure, then the end closuresmay be rendered gas-tight by dipping the end portions only. Thus thewhole package need not be subjected to the heat of a bath of moltencoating substance, a substantial saving of coating substance may beeffected, and a neater vand more attractive package Will be obtained.

Such a package will not loe dependent upon an all-over gas-tight lm forits operation.

The problems involved are complicated and are divisible into varioussections or groups.

First is the problem of providing a web which shall have the` requiredgas-tightness transversely, or as a membrane, and'shall be adaptable tothe required manipulations and use.

The art has not yet produced a paperboard which per se is gas-tight. Noris it feasible in the present state of the art to impregnate boxboard orpaperboard in bulk to impart gas-tightness toit. Some materials, such ascertain waxes can be driven into paperboard, and impregnation may beattained by the use of solvent solutions. But the fibrous nature of thepaperboard makes it exceedingly diicult to obtain a dependable resultover any large surface area. The evaporation of solvent from solutionstends to leave the residue in a porous condition. Most waxes havingsharp melting points, and hence freely enough liquid to have goodsaturating characteristics, tend to be brittle at normal temperatures;and in general, impregnants in paperboard do not remain in continuousand imperforate association with the bers when the paperboard ishandled, scored, bent, or folded.

The employment of surface coating as a membranous gas-proofing forpaperboard webs likewise presents difficulty. If a tough and relativelyhard coating is employed it is likely to split or rupture upon scoringand folding, whereas if a softer substance is used it is likely not onlyto foul the scoring and cutting rules or the make- Y ready(dependingupon the side of the board upon asoaoue my invention, Ilaminate a gas-proof web or composite to boxboard or paperboard,producing a laminated product which may be scored, folded and otherwisehandled as paperboard is handled, and without loss of its gas-proofness.A suitable product or stock may be made in various ways. A web or filmof gas-tight material in sheet form may be laminated to boxboard with asuitable adhesive. For example, glassine laminated to boxboard by meansof rubber derived from latex as in my Patent No. 1,987,225. Or glassinemay be laminated to boxboard with rubbcry or resinous substances derivedfrom latices, emulsions or dispersions, such, for example, as thedispersion of synthetic rubber obtainable under the trade nameDispersite 1760-A." Or a suitable web may be laminated to boxboard bymeans of a thermoplastic or hot-melt substance. To the extent that thelaminant adhesive forms in itself an imperforate and gas-tight coating,gas-tightness of the web or lm becomes less important, so that I do notintend to confine myself to the use of gas-tight webs. The laminantadhesive must in any event be one which will be non-brittle under allconditions of use, and at the same time one which can withstand thestrains of scoring and bending.

Boxboard stocks suitable for my purpose may be made in bulk bylaminating procedures, and may be wound into rolls or cut immediatelyinto sheets of sizes suitable for the formation of cartons.

Before proceeding to a description of a particular preferred boxboardstock, I point out that in the practice of my invention it is necessarythat the gas-proof web, lm or composite be laminated to the outsidesurface of the boxboard, i. e. that surface which is to form theexternal surface of the carton.

As already indicated, the topmost layer of my structure, which I sihallhereinafter refer to as the web, is preferably formed of a materialhighly resistant to the passage of gas as well as durable and flexiblein character. The so-called glassine of commerce, which is a felted webformed yof highly hydrated paper stock, is excellent for the purpose.Certain non-fibrous substances which have high resistance to the passageof gas may likewise be employed, and iilms of ethyl cellulose orcellulose acetate `are exemplary in this connection. Compositestructures Ior laminates may likewise be employed, as for example, ametal foil and glassine laminate disclosed ln my copending applicationentitled Foil-laminated sheeting and method of making it, Serial No.619,854, filed October 2, 1945, now abandoned. My invention is not,however, confined to the use of Webs which are in themselves gas-tight,for the reason that the layer of laminating adhesive (hereinafterreferred to as the skin), may itself be an imperforate nlm of gas-tightsubstance underlying the web and lo-` cated between it and thepaperboard. Hence, I may even employ ordinary papers which are notthemselves gas resisting for the web, providing precautions are taken sothat the end closures formed by dipping penetrate the papers and seal inla gas-tight fashion with the skin.

Best results are obtained with a web which is gas-resistant in itself,the skin serving to adhere the web to the boxboard, to supply moistureand vapor resistance to a web which may not have these qualities initself,` and to enhance the gas-proofness.

The adhesive substance which forms the skinmaybeprodueedlnvariouswaysofvarylng formulae, as has already beenindicated. It should have strong film forming characteristics such as topromote the easy production oi' an imperforate 'and integral layer orskin. It should be strongly 'adhesive to the paperboard and to theexternal web. At all temperatures which the package is to encounter innormal handling, storage and shipment, at least until' it is broughtinto the hands of the ultimate consumer, the skin should remain pliable,tough and non-brittle. The skin should be compatible with the dippingsubstance for covering the ends of the carton, hereinafter to bedescribed. I prefer a laminant which remains pliable when cold, althoughpreferably also devoid of cold flow. Of the available skin substances. Iprefer those which are thermoplastic, and may be applied as hot-melts.

The desirable qualities for the skin are easily secured in compositionscontaining waxes and various resinous substances. By way of a singleexample and without limitation, an entirely satisfactory formula is asfollows:

100 parts paraln of 135 F. melting point,

parts of a mixture (milled together of 25 parts of a medium molecularWeight polybutene such as the one sold under the trade name Vistanex and75 parts parafn wax),

3 parts of a low molecular weight polybutene.

By a medium molecular Weight resin I mean one having a molecular weightof 80,000 to 100,000, the low molecular weight substance beingappreciably below this range.

Another very suitable formula is as follows:

95 parts medium microcrystalline wax, melting point 160 to 165 F.,

25 parts polybutene of medium molecular weight as above,

10 parts Vistac #1, a synthetic hydrocarbon polymer in the form of aviscous liquid acting as a plasticizer.

All parts in the above formulae are by weight.

Other suitable compounds, by way of further example, may be made frommixtures of parain wax, microcrystalline wax, or both, and otherresinous substances such, for example, as ester gum. Many -otheravailable resins are compatible with and contribute the requiredcharacteristics to waxes or waxy compositions.

Referring to Figure l, I have shown a web I of suitable substance, e. g.glassine, vbeing unwound from a roll 2 and passed over and in contactwith one or more coating rolls 3 turning in a bath 5 of the moltenthermoplastic adhesive. By such means a coating of the requiredthickness is applied to the web I, whereupon the coated surface of theweb may be drawn over a heated smoothing bar 'l which unifles thecoating and insures an imperforate skin. The coated glassine or otherweb may then be cornbined with paperboard 9 being withdrawn from a rollI0, the two materials being passed concurrently through combining rollsIl and l2, one or both of which may be heated. The thermoplasticadhesive, reactivated at this point, joins the web I to the paperboard 9with complete surface conformity. The laminated product I3 may be cutapart into sheets as desired by the usual fly knife arrangement I4, thesheets being stacked vas at I 6. If desired, the laminant may be appliedto the paperboard instead of to the glassine or other web.

Figure 2 is representative of a cross-section scoring, preceded byprinting, if desired. The

thermoplastic substance of the above formulae are clear and transparentin thin layers while the glassineis suiciently translucent so thatprinting upon the boxboard 9 will show through the covering very well.The glassine or other web may, however, be printed before or after thesheets are formed, or either the paperboard 9 or the web I or both maybe printed prior to the laminating. As already pointed out, the skin andweb must be aillxed to the outer surface of the paperboard, i. e. thatface of the paperboard which is to form the outside of the carton.Another web and skin may, if desired, be laminated to the inside face ofthe paperboard but this is not necessary and normally presents noadvantage as respects gas-tightness, though it may be desirable forother purposes. The combined weights or thicknesses of the web I, theskin Il and the paperboard 9 will be chosen to give a laminated productof the desired over-all weight or caliper.

I have found that such a laminated product may be cut and scored by theusual means and in the usual way current in the carton art without lossof its gas-proof character. The web should be thin but tough and strong,the paperboard appreciably thicker than the web, and the coating or skinshould have the characteristics set forth above. Since the web coversthe skin, there is no tendency to foul the cutting knives or make-ready.An external skin over the web is not required nor ordinarily desirable,although it does not constitute a departure from the principles of thisinvention.

Nor is the invention limited to the kind, style or dimensions of thecartons produced from the laminated stock made as described. Forordinary purposes, however, a carton of the usual seal end form isdesirable. In Figure 3 I have shown an exemplary blank having body wallsI8, I9, 20 and 2| and a glue flap 22 in articulation in the order named.In this gure dot and dash lines represent lines of score. Seal end aps23, 24, 25 and 26 are articulated respectively to one end of the bodyWalls, their primed counterparts being articulated to the other. Acarton blank so formed may be tubed by the use of common carton tubingmachinery, by being bent on a pair of intermediate score lines with aunion of the glue flap 22 to the free edge of wall Il by means of anadhesive indicated at 21. i

Two additional features are of importance and value in cartons designedfor the purpose of this invention, but are not limitations upon theinvention otherwise than as set forth in the appended claims. As shownin Figure 3, the naps 25 and 25' are preferably cut back slightly alongtheir lateral edges excepting at the ends of these edges, as shown at28. These flaps are the ones which will immediately underlie the lastfolded flaps 23 and 23' in the closed carton. As described in mycopending application Serial No. 538,764, filed June 5, 1944, now PatentNo. 2,412,031, and entitled Cartons for sealing by immersion, thecutting back ,of the lateral edges of the underlying flaps permits acoating of proong substance applied by dipping or the like to form amore dependable seal at a carton closure.

Also where the cartons are to be gassed by certain processes ashereinafter set forth, I prefer to form in the carton walls meanspermitting the more ready insertion of a gassing nozzle or needle. Thesemeans may be actual perforations; but I prefer to form them as tinydepressible tabs demarked partially by a cut line as indicated at 28 inFigure 3. There may be one, two or more of these means as required byany particular gassing procedure.

The use of a gas-proof adhesive 21 is indicated in some forms of myinvention, though in others ordinary adhesives may be employed. Where agas-proof adhesive is required, I prefer to employ a thermoplasticsubstance which may be applied molten to the glue iiap 22. The parts areeither brought together before the adhesive has set or the adhesivecoating is reactivated (preferably by radiant heat) at the time offolding and pressing the parts together.

The use of gas-proof adhesive 21, however, does not solve the problem ofproducing a gastight longitudinal body seam in the carton. The

material of the carton is gas-proof as a membrane; but in anylongitudinal seam (whether the glue flap be lapped inside or outside theadjacent body wall) a gas exchange can occur by infiltration anddiffusion through the body of the paperboard itself. This would be truein a lapped seam even if both surfaces of the boxboard were faced with agas-tight web and skin. Steps therefore have to be taken to prevent suchgas passage.

One way of accomplishing this is to treat the carton in blank for-m asto a longitudinal edge portion. This will be the portion which is to lapan underlying portion in the seam. Thus where the glue iiap is to beadhered to the under side of the opposite body wall, as is preferred inbox manufacture, I treat the edge portion of the said opposite bodywall. Either in a separate treatment of the blanks or in an operationperformed in the tubing machine as the blanks are moved along, I havefound that I can apply to the free edge of the body wall I8 a deposit ofma terial indicated at (see Figures 3, 4 and 6). This deposit has beenrepresented as located on a portion of the inner face of the wall I8 butcovering also the edge portion thereof as at 30a and merging with thecoating or skin I1 lying on the outer surface of the board. It may ormay not overlie the web I, depen-ding upon the mode of its application.

It is not a limitation on my invention as to how far, if at all, thedeposit 30 penetrates the body of the paperboard layer 9. It may beentirely superficial or it may penetrate the board to a very substantialextent. Were it possible to drive it entirely into the board, this wouldnot be objectionable so long as the function hereinafte-r set forth isperformed. The deposit may be a deposit of substance similar to or thesame as the substance of the skin I1, or it may be a modified material,for example ethyl cellulose. It should bond strongly with the paperboardand make a gas-tight connection with the skin I1 and preferably also theweb I.

An edge coating such as that illustrated in Figure 4 may be made bypassing the edge of the board along an adhesive applying means such asthe surface of a roll while moving it also slightly in the transversedirection so as to be sure of covering the edge portion of the flap I8as at 38a. A more convenient apparatus for the purpose is illustrated inFigures 14 and 15 where I have shown a lower coating roll 3| turning Ina pan 32 of suitable adhesive. A spring pressed upper coating roll Isindicated at 33. The lower roll at least will be driven and the edgeportion of the blank as indicated at I8 will be passed between therolls. The lower roll may be relied upon to transfer coating substanceto the upper roll between the passage of blanks, or means including apan of coating substance 34 and transfer rolls 35 and`3Ii may be used toapply adhesive directly to the upper roll 33.

The result of the use of this form of apparatus ls the complete coveringof a marginal portion of the blank with coating substance so that thecoating substance is deposited on both surfaces of the marginal portionof the blank and bridges over and around the edge portion as clearlyindicated in Figure 16. The coating will also be joined or merged aroundthe edge of any end portion of the blank permitted to pass between therolls as shown at 30h. Hence it may be employed for treating the glueflap 22 in types of construction in which the glue flap is adheredoutside the body wall to which it is attached. If it be desired to applythe coating to a marginal portion of the wall I8 only without applyingit to the flaps 23 and 23', it is possible either to separate the rolls3| and 33 during the passage of the end flaps between them or else tomake these rolls in the form of timed spotting rolls with configuredsurfaces which will contact only the desired portion of the blank.

A longitudinal glue seam in a carton is illustrated in Figure 6 wherethe plied structure comprising the boxboard 9, the skin I1 and the web Iforming a part of wall I8 of the carton laps a similar structure formingthe glue flap 22, and is adhered thereto by the gas-proof adhesive 21while the deposit 30 forms, as illustrated, a gastight bridge orconnection between the skin I1 and web I of the wall I8 and theircounterparts in the glue flap 22.

Yet another mode of accomplishing a gastight longitudinal seam in thecarton is illustrated in Figures '1 and 8. Here the carton is rst tubed,the adhesive union of the wall I8 and the glue fiap 22 beingaccomplished by a generous application of the adhesive 21 so that itcomes out to the edge of the seam. After the seam has been formed inthis way a deposit of sealing substance 31 is run along the seam edge insuch a way as to bridge the gap between the adhesive 21 and the skin I1and web I of the wall I8. Preferably the deposit 31 is so produced asalso to contact and bond to the web portion of the glue flap 22.

The deposit 31 may be applied in various ways which may be extrudedwhile molten or plastic from a nozzle and smoothed into position in anysuitable way by means following the nozzle as respects the path oftravel of the blank. Or the deposit may be made in this fashion or byany other suitable means. e. g. a coating disk, and then it may beresotened or liquefied in place by radiant heat applied thereto. Whenusing this mode of forming a longitudinal gas-tight seam, it is well soto proportion the carton parts that the deposit 31 will not cover thescore line by which the glue flap 22 is articulated to the wall 2I.

It is also within the scope of my invention to apply a coating ordeposit of sealing substance over the edge of a longitudinal seam in acarton after the carton has been erected or after it has been filled andclosed. In Figure 11 I have indicated a deposit 31a covering the edge ofthe longitudinal seam in an erected and closed carton. Such a depositmay be applied by means of a grooved coating roller, or in other ways;and may extend onto two contiguous` walls of the carton covering thecorner portion containing the edge of the longitudinalseam.

Deposits 3D and 37. such as have been described, are not fragile and donot appreciably lessen the appearance factor in my cartons. It is,however, within the scope of this invention to cover any such depositwith an external strip of web material which inthis event willpreferably be adhesively joined also to adjacent portions of the web I.

It is possible also to employ over a longitudinal seam in a carton acovering strip of gas-tight substance making a gas-tight juncture withthe web at each side of the longitudinal seam. In Figure l2 I haveillustrated a tubed carton having a longitudnal seam at the juncture ofbody walls I8 and 2|. A coverng strip of material 38 is shown as beingapplied to these walls so as to cover the juncture between them. Thismaterial may be a coated produ-ct comprising a web and a skin similar tothe web and skin laminated to the boxboard in the carton itself and itmay be applied under heat and pressure where the skin is ofthermoplastic substance capable of bonding in a gas-tight manner withthe web on the body walls of the carton.

In Figure 13 I have illustrated how the same effect may be accomplishedby applying a strip of material 39 across the longitudinal seam and ontothe body walls I8 and 2I in an erected, lled and closed carton.

There are various other Ways in which a longitudinal seam in a' cartonmay be treated so as to be rendered gas-tight. One of these is amodiiication of a, procedure shown in my Patent No. 1,980,180, datedNovember 13, 1934, and is illustrated in Figures 17, 18 and 19. Here thecarton blank has been formed as described above from the boxboardlaminate and comprises the same parts. The gluev tab 22 of the carton,however, has been provided with a longitudinally extending line of cut40 which severs the boxboard itself down to the skin I'I withoutsevering the external web I.

As an incident to the operation of tubing this carton as indicated inFigure 17, the blank is moved along in the direction of the arrows and aguide or sweep 4I is employed to bend downwardly that part of the gluetab 22 lying beyond the cut 49. The result of this is to separate theboxboard portions from each other and expose the skin I'I, as it were,in a groove on theinner or boxboard side of the laminate. While theouter portion of the glue tab is still bent downwardly adhesive isapplied to it as by a wheel 42 in such fashion as to coat the exposededges of the boxboard in the cut 49 and merge with the skin Il in agas-tight fashion. The adhesive is indicated at 43 and it will be notedthat it is also applied so as to coat adjacent inner face portions ofthe glue tab.

In the further movement of the container blank it is folded over upontwo longitudinal score lines for tubing by sweeps 44 and 45 or theirequivalent, and in such a way that the glue tab 22 lies outside the wallI8 to which it will be pressed and adhesively secured by means notshown. The result is a seam as illustrated in Figure 19 where the gluetab 22 is joined externally to the wall IB by adhesive 43 which not onlyisbonded in a gas-tight fashion to the web I lacing the wall I8 but alsois bonded as at 4E to the skin on the overlying web I of the glue tab.By this procedure, if it is accurately performed, a gastightlongitudinal seam is effected in the carton with the advantage thatexternal applications of coating substance or of strip material areavoided. A seal will be effected between the cap-like closures formed byend-dipping and the afore-mentioned seam at the ends of the glue tab.

Cartons formed in any of the ways set forth above are folding cartons inknock-down form capable of being shipped as such to the carton user andsquared up. filled and closed by him in the usual fashion and with theusual apparatus for that purpose. The carton user will normally erectthe tubular body and fold and adhesively secure the flaps on one end.This end may then be dipped, if desired, or the carton may first befilled, closed on the remaining open end and dipped on both ends. Theadhesive used in securing the cloture flaps may be any suitable one, notrequiring gas-tight characteristics. The use of a gas-tightthermoplastic is, however, within the scope of my invention.

The dipping may be done by any suitable means or by hand. In forming acompletely gas-tight package with the structure thus far described, Idip only the end portions of the carton, forming as indicated in asomewhat exaggerated way at 4l and 48 in Figure 10 cap-like lms or skinsof thermoplastic adhesive substance covering the entire ends of thecarton and joined in a gas-tight fashion to the web I and to anyportions of the skin I1 which may be exposed at the corners of `same asthe substance used for the skin I'I; but

I prefer to employ a material capable of producing a harder, tougherskin, non-tacky as to surface but capable of retaining its pliabilitythroughout the entire expected range of temperatures to be encounteredby the package as set forth alcove.

Again without limitation, since this formula is exemplary only, I haveused with excellent effect a composition of matter consisting of thefollowing:

40 parts paraillne having a melting point of 40 parts of a material soldby Monsanto Chemical Company under the trade name Aroclor 5460, which isunderstood to be a chlorinated tri-phenyl.

20 parts of a milled mixture" made of '75 parts paraiin wax and 25 partsmedium molecular weight polybutene as defined above.

'Ihis milled mixture is obtainable on the market under the trade nameTervan. 'I'he composition above is substantially water white in color orvery slightly yellow and is capable of forming thin, tough films ofexcellent gas-tightness and very neat appearance.

The manner in which special atmospheres are introduced into my packagesdoes not form a. limitation upon this invention. A heavier than airatmosphere may be introduced into the package along with the contentsand the package may be rendered gas-tight by end dipping rapidly enoughto minimize diiusion and loss of the special atmosphere. It is, however,preferred to effect atmospheric exchange by methods taught in mycopending applications referred to hereinabove. In each of thesemethods, after the formation of a gas-tight package, the package wallsare perforated. In the first method the packages, introduced into aclosed chamber are iirst vacuumized and then lled with the desiredspecial atmosphere. In the second method a hollow needle is introducedinto the package and the initial 4air is displaced by blowing thespecial atmosphere into the package through the hollow needle, therebeing an exit for the contained air preferably located as far aspossible within the coniines of the package from the point ofintroduction of the special atmosphere, i. e. the end of the needle. Inboth processes the walls of the package are not subjected to appreciabledifferences between internal and external atmospheric pressures.

In the cartons of the present invention, periorations may be made bypunching inwardly the tiny tab or tabs demarked by the lines ofweakening 29, or by inserting gassing or exit nozzles through them,without danger of tearing the carton walls. In both processes as soon asatmospheric exchange has been effected, the opening or openings formedin the package walls are sealed. This may be done by depositing overthe' opening or openings masses of a thermoplastic sealing compositionor by closing the openings with a patch 48 (Figure 10) comprising a webbearing a lm or skin of gas-tight thermoplastic.

Whereas in the packages described in those cases there was an external,over-all coating of gas-tight character to which the perforationclosures just mentioned were caused to adhere and withY which theclosure composition was caused to merge, in my present packages similarclosure means are bonded by means of the gas-tight thermoplastic to theexternal web l and its skin l1 to the extent that that skin is exposed.

By the described means I am enabled to produce dependable gas-tight andgassed packages,

capable of retaining their special atmospheres over long periods of useand for sufficient lengths of time to meet the requirements of theordinary commercial distribution of products requiring such protection.The practice of my invention does not exclude differences in externaland internal pressures, but in actual practice the internal and externalpressures as respects my packages are preferably the same orsubstantially the same at normal or room temperatures. The flexibilityof the walls of my packages takes care oi differences in pressurenaturally occurring due to barometric and temperature changes unlessthese -be excessive. In packages which have been perforated and gassedby atmospheric exchange in the ways set forth above, closures for theperforations embodying webs and adhesives soft enough to be self-sealingmay be arranged to afford relief from excessive internal pressures ifdesired, though this is not necessary in ordinary practice.

Modifications may be made in my invention without departing from thespirit of it. Having described my invention in certain exemplaryembodiments, what I claim as new and desire to secure by Letters Patentis:

1. A moisture, vapor and gas-tight package of iiexible materials andcomprising a tubed paperboard carton formed from a blank consisting ofbody walls in articulation and closure ilaps at the ends of body walls,means for rendering the body formed by such tubed body walls gastightcomprising a skin of exible gas-proof composition and an overlyingprotective web joined to said body walls by said skin and tubedtherewith with a gas-tight longitudinal seam, said carton being inclosed condition, and end closure means overlying said closure flaps andcomprising an imperforate skin of ilexible gas-proof composition bondedin a gas-tight manner to said web peripherally of the carton ends, saidclosure means being spaced from each other, and said means for renderingthe said body gas-tight bridging the gap between said closure means andcoacting therewith to impart moisture, vapor and gas-tightness to saidpackage.

2. The structure claimed in claim 1 in which said longitudinal seamincludes a deposit of gasproof composition connecting lapped portions ofsaid web and first mentioned skin about an otherwise free edge ofpaperboard of said carton.

3. The structure claimed in claim 1 in which seid longitudinal seamincludes a member comprising a skin and web bridging the gap betweenlapped portions of said iirst mentioned skin and web about an otherwisefree edge of the paperboard of said carton.

4. A process of making a, moisture, vapor and gas-tight package ofilexible materials which comprises providing a paperboard carton blankhaving body walls in articulation and closure flaps, applying to theentire surface of the blank which will constitute the exterior of thecarton, a means for rendering said body walls gas-tight, said meanscomprising a skin of exible gasproof composition and an overlyingprotective web joined to said body walls and aps in said blank,concurrently tubing said carton blank and forming in said blank, skinand web a longitudinal gas-tight seam, filling said carton and closingsaid carton flaps and applying end closure means therefor comprisingeach an imperforate skin of nexible gas-proof composition covering theend of said carton, and bonding said skin in a gas-tight manner to saidfirst mentioned skin and web peripherally of the ends of said carton,said closure means being spaced by the carton body and said means forrendering the said body gas-tight bridging the gap between said endclosure means and coacting therewith to impart moisture, vapor andgas-tightness to said package.

5. The process claimed in claim 4 including the steps of joining saidrst mentioned skin and web to paperboard and forming said carton' byconcurrently cutting and scoring said paperboard, said skin and saidweb.

6. The process claimed in claim 4 including the steps of depositing atsaid longitudinal seam a mass of gas-tight composition bridging the gapbetween lapped portions of said irst mentioned skin and web around anotherwise free edge of said paperboard.

7. The process claimed in claim 4 including the step of covering saidlongitudinal seam with a member comprising a skin and web joininglapping portions of said rst mentioned skin and web about an otherwisefree edge of said paperboard.

8. The process claimed in claim 4 in which said end closure means areprovided by dipping 13 ends only of said package in a heat molten,thermoplastic, gas-proof composition whereby to form at said endscap-like closures having a body portion lying transverse to the bodyWalls of said carton and additional portions lapping ends of 5 said bodywalls. Y

SAMUEL BERGSTEIN.

REFERENCES CITED UNITED STATES PATENTS Name Date Jenkins June 22, 1909 uNumber Number 14 Name Date Eckstein Nov. 27, 1928 Wesselman June 2, 1936Howard July 21, 1936 Magill June 29, 1937 Wesselman Dec. 13, 1938 Swan,3d June 20, 1939 Waters Dec. 3, 1940 Waters Aug. 12, 1941 Kienlen Oct.21, 1941 Berch Dec. 2:3, 1941 Waters June 5, 1945 Glmllan July 31, 1945

